Various ceramics are used for jigs for semiconductor production apparatus for an oxidation diffusion process, a CVD (hereinafter sometimes referred to also as chemical vapor deposition) process, or, in recent years, a plasma etching process. Among them, ceramics made of silicon carbide (hereinafter referred to as SiC ceramics) are widely used as parts for semiconductor production apparatus, since they are materials excellent in thermal conductivity, heat resistance and acid resistance.
For ceramic products for semiconductor production apparatus, a complex shape or a large size shape may be required in many cases. However, ceramics including SiC ceramics, are usually hardly processable. It is difficult in many cases to produce e.g. a sintered body of a complex shape by unified processing, and also with respect to a large size shape, it is impossible in many cases to produce such a product from a restriction of the production facility such as a calcination furnace.
Accordingly, it is common to divide a desired product into a plurality of parts (hereinafter referred to also as elements) and to join the respective parts to obtain a final product (a joined product).
Heretofore, as a common joining method for ceramic parts, joining by means of a binder in a state prior to calcination, or joining by means of an organic or inorganic binder after calcination, has been, for example, known. However, the joining by means of a binder prior to calcination has had a problem that it is cumbersome, and no correction is feasible after calcination. On the other hand, the joining by means of a binder after calcination has had a serious problem that it is inferior in strength or air tightness, and the purity tends to deteriorate. Further, by such a conventional joining method, it has been difficult to mend a broken product.
Further, JP-A-10-87376 proposes a method wherein SiC parts having male and female joining portions, are combined, so that a gap formed by the joining portions, is continuous, and molten Si is filled and solidified in the gap for joining. However, there has been a problem with respect to the heat resistance and acid resistance of the Si portion which fills the gap.
On the other hand, JP-A-9-249455 proposes a method wherein carbon parts are assembled, they are joined by means of a thermosetting resin adhesive containing carbon particles, to obtain a joined body, then the joined body including the adhesive portion, is converted to SiC, and further, on its surface, a SiC coating film is formed by a chemical vapor deposition method. However, this method employs a resin adhesive, whereby the strength of the joint portion tends to be weak, and there has been a problem that since carbon parts are used as the starting members, the method includes many steps and requires cumbersomeness.
Further, JP-A-9-107024 proposes that at the time of producing a graphite product having a SiC coating film formed, graphite products are joined by bringing them in close contact by face-to-face contact, and then a SiC coating film is formed by a chemical vapor deposition method. However, as the substrate parts, graphite having low strength is used, and it is difficult to firmly adhere them by face-to-face contact. Further, it is also proposed to fill a gap between joining surfaces with a sealing material made of a high temperature adhesive, followed by heat treatment for carbonization to secure the adhesion. However, fundamentally, graphite or the like as the substrates and the SiC coating film are different in the thermal expansion coefficients, and it is difficult to always maintain the adhesion.
Namely, heretofore, it has been difficult to find a joining method whereby high-purity ceramic parts can be joined simply without lowering the purity, yet, the obtainable joined body is excellent in high temperature strength, heat resistance and corrosion resistance, and it is applicable also to a complex shape.